Display structure and display device

Abstract

A display structure (1000) includes: a waveguide (1100) including a first surface (1110), a second surface (1120) opposite to the first surface (1110), and an input coupling region (1112) located on the first surface (1110); an input coupling structure (1200) for coupling a light beam (1201) into the waveguide (1100) via the input coupling region (1112); and an output coupling structure (1300) configured to perform an outgoing pupil expansion by pupil replication and couple light from the light beam (1201) to the outside of the waveguide (1100). The input coupling region (1112) has a maximum width Wmax; the waveguide (1100) has a thickness T greater than 0.25×Wmax; and the output coupling structure (1300) includes a first output coupling element (1310) that diffracts and a second output coupling element (1320) that diffracts and at least partially overlaps the first output coupling element (1310) laterally.

Description

[Technical Field]

[0001] This invention relates to display devices, and more particularly to waveguide-based display devices and structures having exit pupil expansion properties. [Previous Technology]

[0002] Waveguide-based display devices with extended exit pupils are commonly used in various applications, such as head-mounted transmissive display devices (e.g., smart glasses).

[0003] Generally, such devices must be carefully designed to limit optical losses associated with light coupling to the waveguide. Conventionally, such optical input coupling losses can be reduced by using polarization-dependent coupling structures, such as polarization-dependent diffraction gratings, combined with polarization-altering elements, such as waveplates. However, such an arrangement can increase the complexity of the display device.

[0004] In view of the above, it is desirable to develop a new structure related to waveguide-based display devices. [Summary of the Invention]

[0005] The present invention provides a simplified description of some selected concepts, which will be further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed content, nor is it intended to limit the scope of the claimed content.

[0006] According to a first aspect, a display structure is provided. The display structure includes: a waveguide including a first surface extending laterally along a reference surface, a second surface opposite to the first surface, and an input coupling region located on the first surface; an input coupling structure for coupling a light beam into the waveguide via the input coupling region to propagate in the waveguide by total internal reflection; and an output coupling structure configured to perform an exit pupil expansion by pupil replication along at least a first replication direction and to couple light from the light beam out of the waveguide. The input coupling region has a maximum width measured along the first replication direction; the waveguide has a thickness measured from the first surface to the second surface that is greater than 0.25 times the maximum width of the input coupling region; and the output coupling structure includes a diffracting first output coupling element and a diffracting second output coupling element that at least partially overlaps the first output coupling element laterally.

[0007] According to a second aspect, a display device is provided, including a display structure according to a first aspect. [Simplified Explanation of the Diagram]

[0008] A better understanding of this disclosure will be achieved by reading the following detailed description in conjunction with the accompanying drawings, wherein:

[0009] Figure 1 shows a display structure according to one embodiment.

[0010] Figure 2 shows another display structure according to one embodiment.

[0011] Figure 3 shows another display structure according to one embodiment.

[0012] Figure 4 shows a display device according to one embodiment.

[0013] Unless otherwise specified, none of the figures in the drawings are drawn to scale, and any element in the figures may be drawn at an inaccurate scale relative to other elements in the figures in order to emphasize a particular structural orientation of an embodiment of the figures.

[0014] Furthermore, corresponding elements in embodiments of any two of the drawings may be disproportionate to each other in the two drawings to emphasize a particular structural aspect of the embodiments of the two drawings.

Implementation Method

[0015] Figure 1 shows a display structure 1000 according to an embodiment.

[0016] In this specification, "display device" or "screen" may refer to an operable device suitable for or configured to display visual images to a user, such as an electronic device. Additionally or alternatively, display device may refer to an electronic visual display device. Display devices may generally include any components or elements necessary or beneficial to their operation, such as optical and / or electrical / electronic components or elements.

[0017] In addition, "display structure" may refer to at least a portion of an operable display device. Additionally or alternatively, display structure may refer to a structure used in a display device.

[0018] In the embodiment of FIG1, the structure 1000 is shown to include a waveguide 1100.

[0019] In this disclosure, "waveguide" may refer to an optical waveguide. Additionally or alternatively, a waveguide may refer to a two-dimensional waveguide, wherein light can be confined along the thickness direction of the waveguide. Of course, "waveguide" may refer to a waveguide layer, wherein light can be confined by total internal reflection.

[0020] The waveguide 1100 of the embodiment of FIG1 includes a first surface 1110 extending along a reference surface 1111, a second surface 1120 opposite to the first surface 1110, and an input coupling region 1112 located on the first surface 1110.

[0021] In this disclosure, the “face” of a waveguide may refer to a portion of the surface of the waveguide viewed from or facing a certain observation direction. Additionally or alternatively, the face of a waveguide may refer to a surface adapted or configured to confine light in the waveguide by total internal reflection.

[0022] In this specification, "region" may refer to a portion of a surface. Therefore, an "input coupling region" on a first surface of the waveguide may refer to a region on the first surface adapted or configured to receive light to be coupled into the waveguide for propagation in the waveguide via total internal reflection. Additionally or alternatively, the input coupling region of a waveguide including a display structure of a display engine may refer to the intersection of the entrance region of the input coupling structure and the maximum illuminateable region of the display engine, wherein the input coupling region of a waveguide excluding a display structure of a display engine may refer to the entrance region of the input coupling structure.

[0023] Here, "reference plane" can refer to a virtual surface along which the first face of the waveguide extends. For example, if the first face is flat, the reference plane can be planar, or if the first face is curved, the reference plane can be curved. Furthermore, "extending laterally along the reference plane" of the first face of the waveguide can mean that the first face has a lateral direction along the reference plane. Generally, the lateral extent of a component can be defined by projecting the component onto the reference plane.

[0024] In the embodiment of FIG1, the display structure 1000 includes an input coupling structure 1200.

[0025] In this disclosure, "input coupling structure" can refer to a structure adapted or configured to couple a light beam into a waveguide for propagation within the waveguide via total internal reflection. Generally, an input coupling structure can be adapted or configured to couple a light beam into the waveguide via an entry region on a first surface of the waveguide. For example, the entry region of an input coupling structure including a diffractive input coupling element can refer to a region on the first surface, the lateral extent of which is defined by the lateral extent of the diffractive input coupling element. Similarly, the entry region of an input coupling structure including an input coupling prism can refer to a region on the first surface, the lateral extent of which is defined by the lateral extent of the face of the input coupling prism coupled to the waveguide.

[0026] The input coupling structure 1200 of the embodiment of FIG1 is adapted to couple the light beam 1201 into the waveguide 1100 through the input coupling region 1112 so as to propagate in the waveguide 1100 by total internal reflection.

[0027] In this specification, "beam" may refer to the directional flow of light radiated from a light source.

[0028] In the embodiment of FIG1, the display structure 1000 includes an output coupling structure 1300.

[0029] In this disclosure, "output coupling structure" may refer to a structure configured to couple light to the outside of a waveguide.

[0030] The output coupling structure 1300 of the embodiment of FIG1 is configured to perform outgoing pupil expansion by pupil replication along at least a first replication direction 1301 and to couple light from beam 1201 to the outside of waveguide 1100.

[0031] Here, "exit pupil expansion" can refer to a process in which light is distributed in a controlled manner within a waveguide to expand the portion of the waveguide that generates optical output coupling.

[0032] Furthermore, "pupil replication" can refer to the process of expanding the outgoing pupil, in which multiple outgoing sub-pupils are formed in the imaging system. It is known that in imaging systems that rely on pupil replication to expand the outgoing pupil, each outgoing sub-pupil is preferably arranged in an overlapping manner across the lateral range of the waveguide's output coupling region for all angles and all wavelengths. This arrangement of the outgoing sub-pupils avoids the formation of spatial intensity variations in the output coupled image, which are typically perceived as dark stripes.

[0033] In this specification, "first copying direction" may refer to the direction in which the output coupling structure is configured to perform pupil copying. Additionally or alternatively, the first copying direction may refer to a direction extending parallel to the reference plane.

[0034] Furthermore, the output coupling structure configured to perform "pupil replication along at least a first replication direction" may refer to the output coupling structure being configured to perform, for example, one-dimensional pupil replication in a horizontal or vertical direction, or, for example, two-dimensional pupil replication in a horizontal and vertical direction.

[0035] In the embodiment of FIG1, the input coupling region 1112 has a maximum width (Wmax), the thickness (T) of the waveguide 1100 is greater than 0.25×Wmax, and the output coupling structure 1300 includes a diffracting first output coupling element 1310 and a diffracting second output coupling element 1320, wherein the diffracting second output coupling element 1320 and the first output coupling element 1310 overlap laterally at least partially, that is, partially or completely laterally.

[0036] Generally speaking, the output coupling structure of a display structure including a diffracting first output coupling element and a diffracting second output coupling element that is at least partially laterally overlapped with the first output coupling element can help increase the thickness of the waveguide in order to limit optical coupling loss and / or increase the mechanical stability of the waveguide without impairing the optical properties of the display structure.

[0037] Here, the "maximum width" of the input coupling region may refer to a measurement of the range of the input coupling region along the first replication direction, such as a maximum measurement. For example, in the case that the input coupling region is circular, the maximum width of the input coupling region may refer to the diameter of the input coupling region.

[0038] Furthermore, the "thickness" of the waveguide may refer to a measurement of the range of the waveguide from the first surface to the second surface. Alternatively or additionally, the thickness of the waveguide may be measured perpendicular to the reference surface. Alternatively or additionally, the thickness of the waveguide may be measured from the input coupling region to the second surface.

[0039] In this specification, "diffractive optical element" can refer to an optical element whose operation is based on the diffraction of light. Generally, a diffractive optical element may include structural features having at least one dimension on the order of visible light wavelengths, for example, less than one micrometer in at least one dimension. Typical examples of diffractive optical elements include one-dimensional and two-dimensional diffraction gratings, which can be implemented as single-region diffraction gratings or multi-region diffraction gratings. Diffraction gratings can typically be implemented at least as surface relief diffraction gratings or volume holographic diffraction gratings, and can be configured to be used as transmissive and / or reflective diffraction gratings.

[0040] Therefore, "diffraction output coupling element" can refer to a diffraction optical element that forms part of an output coupling structure. Additionally or alternatively, diffraction output coupling element can refer to a diffraction optical element adapted or configured to facilitate exit pupil expansion and coupling light to the outside of the waveguide by pupil replication along at least a first replication direction.

[0041] In addition, the first element "at least partially overlaps laterally" and the second element may refer to the projections of the first element and the second element on the reference plane being at least partially overlapping, that is, partially or completely overlapping.

[0042] In the embodiment of FIG1, waveguide 1100 may be formed of glass. In other embodiments, the waveguide may include or be formed of any suitable material, such as glass or polymer.

[0043] In the embodiment of FIG1, waveguide 1100 may have a refractive index of approximately 2 across the entire visible spectrum. In other embodiments, the waveguide may have any suitable refractive index and any suitable dispersion characteristics.

[0044] In the embodiment of FIG1, the waveguide 1100 is bounded by air, which has a refractive index of approximately 1 across the entire visible spectrum. Therefore, the beam 1201 is confined within the waveguide 1100 by total internal reflection at the two air-glass interfaces. In other embodiments, the waveguide may or may not be bounded by air.

[0045] Although not depicted in FIG1, the output coupling structure 1300 may be configured to perform outgoing pupil expansion by pupil replication along a second replication direction other than the first replication direction 1301. In such a case, each of the first output coupling element 1310 and the second output coupling element 1320 may include a two-dimensional diffraction grating. In other embodiments, the output coupling structure may be configured to perform outgoing pupil expansion by pupil replication along the second replication direction, or it may be configured not to perform outgoing pupil expansion by pupil replication along the second replication direction. In other embodiments where the output coupling structure is configured to perform outgoing pupil expansion by pupil replication along the second replication direction, one or both of the first and second output coupling elements may include a two-dimensional diffraction grating.

[0046] In some embodiments, the output coupling structure of the display structure may be configured to replicate via a pupil along a first replication direction, and one or both of the first and second output coupling elements may include a one-dimensional diffraction grating. In such embodiments, the display structure may further include an intermediate pupil expansion structure, or may not further include an intermediate pupil expansion structure, which is configured to receive light from the input coupling structure, perform outgoing pupil expansion by replicating the pupil along a second replication direction different from the first replication direction, and guide the light to the output coupling structure.

[0047] In the embodiment of FIG. 1, the thickness T of waveguide 1100 may be approximately 0.3 times the maximum width Wmax of the input coupling region 1112. In other embodiments, the waveguide may have any suitable thickness greater than 0.25 times the maximum width of the input coupling region. In some embodiments, the thickness of the waveguide may be greater than or equal to 0.3 times, 0.35 times, or 0.4 times the maximum width of the input coupling region. Generally, the thickness of the waveguide is proportional to the maximum width of the input coupling region and can increase its mechanical stability and / or reduce input coupling losses in the display structure by reducing the output coupling effects associated with multiple interactions with the input coupling structure.

[0048] In the embodiment of FIG. 1, the thickness T of waveguide 1100 is less than 0.5 × Wmax. In other embodiments, the waveguide may have a thickness less than or equal to 0.5 times the maximum width of the input coupling region, or it may not have a thickness less than or equal to 0.5 times the maximum width of the input coupling region. Generally, a waveguide with a thickness less than or equal to 0.5 times the maximum width of the input coupling region can help to form a higher quality output coupled image, even in the absence of output coupling elements other than the first and second output coupling elements.

[0049] In the embodiment of FIG. 1, the thickness T of waveguide 1100 can be approximately 0.8 mm. In other embodiments, the waveguide can have any suitable thickness, for example, a thickness greater than or equal to 0.2 mm, or greater than or equal to 0.5 mm, and / or less than or equal to 2 mm, or less than or equal to 5 mm. Generally, increasing the thickness of the waveguide can facilitate the fabrication of the display structure.

[0050] In the embodiment of FIG1, the maximum width Wmax of the input coupling region 1112 can be approximately 2.5 mm. In other embodiments, the input coupling region can have any suitable maximum width, for example, a maximum width greater than or equal to 0.5 mm, or greater than or equal to 1 mm, and / or less than or equal to 5 mm, or less than or equal to 10 mm.

[0051] In the embodiment of FIG1, the input coupling structure 1200 includes a diffraction input coupling element 1210. In other embodiments, the input coupling structure may or may not include a diffraction input coupling element. Generally, an input coupling structure including a diffraction input coupling element can help reduce the quality of the display structure.

[0052] The diffraction input coupling element 1210 of the embodiment of FIG1 includes a surface-roughened diffraction grating. In other embodiments where the input coupling structure includes a diffraction input coupling element, the diffraction input coupling element may or may not include a surface-roughened diffraction grating. For example, in some such embodiments, the input coupling structure may include a volumetric holographic diffraction grating.

[0053] The diffraction input coupling element 1210 of the embodiment in FIG1 is disposed on the first surface 1110. In other embodiments, the diffraction input coupling element may be disposed on the first surface of the display structure, or it may not be disposed on the first surface of the display structure. For example, in some embodiments, the diffraction input coupling element may be disposed on the second surface or within the waveguide.

[0054] The output coupling structure 1300 of the embodiment in FIG1 is configured to couple light to the outside of the waveguide 1100 via the first surface 1110. In other embodiments, the output coupling structure may be configured to couple light to the outside of the waveguide via the first surface and / or the second surface.

[0055] In the embodiment of FIG1, the first output coupling element 1310 is disposed on the first surface 1110, and the second output coupling element 1320 is disposed on the second surface 1120. In other embodiments, the first output coupling element may be disposed on the first surface or not, and / or the second output coupling element may be disposed on the second surface or not. For example, in some embodiments, the first output coupling element and / or the second output coupling element may be disposed within the waveguide. Generally, disposing the first output coupling element and / or the second output coupling element on the surface of the waveguide can facilitate the fabrication of the display structure.

[0056] Each of the first output coupling element 1310 and the second output coupling element 1320 includes a surface-roughened diffraction grating. In other embodiments, one or both of the first and second output coupling elements may include a surface-roughened diffraction grating, or may not include one. In some embodiments, both the first and second output coupling elements include a volumetric holographic diffraction grating. In embodiments where one of the first and second output coupling elements includes a surface-roughened diffraction grating, the other may include a volumetric holographic diffraction grating.

[0057] In the embodiment of FIG. 1, the surface undulation diffraction gratings of the first output coupling element 1310 and the second output coupling element 1320 are formed in patterned films disposed on the waveguide 1100. In other embodiments where the first output coupling element and / or the second output coupling element includes a surface undulation diffraction grating, the surface undulation diffraction grating may be formed in the patterned films disposed on the waveguide, or it may not be formed in the patterned films disposed on the waveguide. For example, in some such embodiments, the surface undulation diffraction grating may be formed directly in the waveguide.

[0058] Although the surface undulation diffraction gratings of the diffraction input coupling element 1210, the first output coupling element 1310, and the second output coupling element 1320 are schematically depicted as binary diffraction gratings in FIG1, any suitable type of surface undulation diffraction grating can be used for any or all of the diffraction input coupling element, the first output coupling element, and the second output coupling element, such as binary, and / or blazed, and / or slanted, and / or multi-level, and / or analog diffraction gratings. Of course, such surface undulation diffraction gratings can be configured with additional features, such as spatial diffraction efficiency modulation properties, to improve waveguide efficiency and image uniformity in any suitable manner, such as through depth, duty cycle, or slant modulation.

[0059] Furthermore, although Figure 1 depicts a single waveguide 1100, the display structure typically includes one or more waveguides. In embodiments where the display structure includes two or more waveguides, the waveguides can be arranged in any suitable manner. In some such embodiments, such waveguides can be stacked on top of each other.

[0060] FIG2 illustrates a display structure 2000 according to one embodiment. The embodiment of FIG2 may be based on any embodiment disclosed with reference to or in conjunction with FIG1. ​​Additionally or alternatively, although not explicitly shown in FIG2, the embodiment of FIG2 or any part thereof may generally include any features and / or elements of the embodiment of FIG1.

[0061] In the embodiment of FIG2, the display structure 2000 includes: a waveguide 2100 including a first surface 2110 extending along a reference surface 2111, a second surface 2120 opposite to the first surface 2110, and an input coupling region 2112 located on the first surface 2110; an input coupling structure 2200 for coupling a light beam 2201 into the waveguide 2100 via the input coupling region 2112 to propagate in the waveguide 2100 by total internal reflection; and an output coupling structure 2300 configured to perform an exit pupil expansion by pupil replication along at least a first replication direction 2301 and couple light from the light beam 2201 to the outside of the waveguide 2100.

[0062] The input coupling region 2112 has a maximum width (Wmax) measured along the first replication direction 2301, and the waveguide 2100 has a thickness (T) from the first surface 2110 to the second surface 2120, which is greater than 0.25 times Wmax. The output coupling structure 2300 includes a diffracting first output coupling element 2310 and a diffracting second output coupling element 2320 that at least partially overlaps the first output coupling element 2310 laterally.

[0063] In the embodiment of FIG2, the input coupling structure 2200 includes an input coupling prism 2220. The input coupling prism 2220 is attached to the waveguide 2100. In other embodiments, the input coupling structure may or may not include an input coupling prism.

[0064] In the embodiment of FIG2, the first output coupling element 2310 is disposed on the first surface 2110, and the second output coupling element 2320 is disposed on the second surface 2120.

[0065] Each of the first output coupling element 2310 and the second output coupling element 2320 includes a surface-roughened diffraction grating. The surface-roughened diffraction grating of the first output coupling element 2310 is formed in a patterned thin film disposed on the waveguide 2100, while the surface-roughened diffraction grating of the second output coupling element 2320 is formed directly in the waveguide 2100. In other embodiments, one or both of the first and second output coupling elements may be formed directly in the waveguide, or they may not be formed directly in the waveguide.

[0066] As shown by the dashed lines in FIG2, the output coupling structure 2300 of the embodiment of FIG2 may further include a diffracted third output coupling element 2330 disposed within the waveguide 2100, the third output coupling element 2330 at least partially laterally overlapping each of the first output coupling element 2310 and the second output coupling element 2320. In other embodiments, the output coupling structure may or may not include such a diffracted third output coupling element. Generally, an output coupling structure including a diffracted third output coupling element that overlaps with each of the first and second output coupling elements and is disposed within the waveguide can further increase the density of the exit pupil, which in turn can help to further increase the thickness of the waveguide without compromising the optical properties of the display structure.

[0067] In some embodiments, the output coupling structure includes a diffracting third output coupling element disposed within the waveguide and at least partially laterally overlapping each of the first and second output coupling elements. The output coupling structure may further include one or more additional output coupling elements, each of which is disposed within the waveguide and overlaps each of the first, second, and third output coupling elements.

[0068] In the embodiment of FIG2, where the output coupling structure 2000 includes a third output coupling element 2330, T can be greater than or equal to 0.5 × Wmax, or greater than or equal to 0.6 × Wmax, or greater than or equal to 0.7 × Wmax, or greater than or equal to 0.8 × Wmax, or greater than or equal to 0.9 × Wmax. In other embodiments, where the output coupling structure includes a third output coupling element disposed within a waveguide and at least partially laterally overlapping each of the first and second output coupling elements, the waveguide can have any suitable thickness greater than 0.25 times the maximum width of the input coupling region.

[0069] The third output coupling element 2330 of the embodiment of FIG2 may include a volumetric holographic diffraction grating. The volumetric holographic diffraction grating of the third output coupling element 2330 may be implemented as a so-called thin transmission volumetric holographic diffraction grating, having a thickness of less than 0.1 mm and being used as a transmission grating. The volumetric holographic diffraction grating of the third output coupling element 2330 may also be implemented as a so-called "thick" volumetric holographic diffraction grating, having a thickness of at least 0.1 mm and being used as a transmission and / or reflection diffraction grating.

[0070] FIG3 illustrates a display structure 3000 according to one embodiment. The embodiment of FIG3 may be based on or in conjunction with any embodiment disclosed in FIG1 and FIG2. Additionally or alternatively, although not explicitly shown in FIG3, the embodiment of FIG3 or any part thereof may generally include any features and / or elements of the embodiments of FIG1 and FIG2.

[0071] In the embodiment of FIG3, the display structure 3000 includes a waveguide 3100, the waveguide 3100 including a first surface 3110 extending laterally along a reference plane 3111, and an input coupling region 3112 located on the first surface 3110. The display structure 3000 further includes an input coupling structure 3200 and an output coupling structure 3300. The input coupling structure 3200 includes a diffraction input coupling element 3210 for coupling a light beam 3201 into the waveguide 3100 via the input coupling region 3112 to propagate in the waveguide 3100 by total internal reflection. The output coupling structure 3300 is configured to perform an exit pupil expansion by pupil replication along at least a first replication direction 3301 and couple light from the light beam 3201 to the outside of the waveguide 3100.

[0072] The display structure 3000 of this embodiment further includes a display engine 3400 for guiding the beam 3201 to the input coupling structure 3200. In other embodiments, the display structure may or may not include such a display engine.

[0073] In this disclosure, "display engine" can refer to a part of a display structure adapted or configured to form an image to be transmitted to an input coupling structure, for example, in an angular spectrum. Generally, the display engine may have a (maximum) illuminated area on a first surface of the waveguide. The illuminated area of ​​the display engine may laterally overlap at least partially with the entrance region of the input coupling structure, that is, partially or completely with the entrance region of the input coupling structure. The display engine may or may not form an exit pupil. In embodiments where the display engine forms an exit pupil, the exit pupil may overlap with the entrance pupil of the input coupling structure.

[0074] The display engine 3400 of the embodiment in FIG3 is implemented as a scanner-based display engine. In other embodiments where the display structure includes a display engine, the display engine can be implemented in any suitable manner, for example, as a scanner-based display engine or as a panel-based display engine. Generally, the use of a scanner-based display engine can help reduce the size of the display structure and / or increase brightness and / or increase the contrast of the display structure. Since the use of a scanner-based display engine typically produces a smaller illuminated area, a waveguide with reduced thickness can be used in conjunction with such a display engine.

[0075] In the embodiment of FIG3, the display engine 3400 includes: an illumination unit 3410, including a first laser 3411 emitting blue light, a second laser 3412 emitting green light, and a third laser 3413 emitting red light; a combination unit 3420, for combining the light from the first laser 3411, the second laser 3412, and the third laser 3413 to form a light beam 3201; and a scanner unit 3430, including a first deflector 3431 and a second deflector 3432, for collecting the light from the combination unit 3420 and driving the first deflector 3431 and the second deflector 3432 so that the light beam 3201 illuminates different positions on the input coupling region 3112.

[0076] The display engine 3400 of the embodiment in FIG3 includes a laser-based illumination unit. In other embodiments, the display engine may include any suitable type of illumination unit, such as a laser-based illumination unit and / or a light-emitting diode-based illumination unit.

[0077] The scanner unit 3430 of the embodiment in FIG3 can be implemented as a dual one-dimensional micro-electro-mechanical mirror scanner unit. In other embodiments, the scanner-based display engine may include any suitable type of scanner unit, such as a dual one-dimensional micro-electro-mechanical mirror (MEMS mirror) scanner unit or a two-dimensional MEMS mirror scanner unit.

[0078] On one hand, the input coupling structure 3200 of the embodiment in FIG3 has an entry region 3202 on the first surface 3110, the entry region 3202 being defined by the lateral extent of the diffraction coupling element 3210. On the other hand, the display engine 3400 has an illuminated region 3401 on the first surface 3110. The lateral extent of the illuminated region 3401 depends on the range of motion of the first deflector 3431 and the second deflector 3432.

[0079] As an embodiment of FIG3, the display structure 3000 includes a display engine 3400, and the lateral extent of the input coupling region 3112 is defined as the intersection of the entrance region 3202 and the illuminated region 3401. In the embodiment of FIG3, the input coupling region 3112 has a maximum width Wmax measured along the first replication direction 3301; the waveguide 3100 has a thickness T, which is greater than 0.25 × Wmax; and the output coupling structure 3300 includes a diffracting first output coupling element 3310 and a diffracting second output coupling element 3320 that at least partially overlaps the first output coupling element 3310 laterally.

[0080] In the embodiment of FIG3, waveguide 3100 may have a T of approximately 0.5 mm, and input coupling region 3112 may have a Wmax of approximately 1.2 mm. Therefore, T may be approximately 0.4 × Wmax.

[0081] The above mainly discussed the characteristics of the display structure. The following will place greater emphasis on the characteristics of the display device. The above description of the implementation methods, definitions, details, and advantages of the display structure applies in comparison to the display device discussed below, and vice versa.

[0082] FIG4 illustrates a display device 4000 according to one embodiment. The embodiment of FIG4 may be based on any embodiment disclosed with reference to or in conjunction with FIG1 to FIG3. Additionally or alternatively, although not explicitly shown in FIG4, the embodiment of FIG4 or any part thereof may generally include any features and / or elements of the embodiments of FIG1 to FIG3.

[0083] The display device 4000 of the embodiment of FIG4 includes a display device based on this specification.

[0084] In the embodiment of FIG4, the display device 4000 is implemented as a see-through head-mounted display device, more specifically, as eyeglasses including a see-through display. In other embodiments, the display device may be implemented in any suitable manner, for example, as a see-through and / or head-mounted display device.

[0085] In the embodiment of FIG4, the display device 4000 includes a waveguide 4100, an input coupling structure 4200, an output coupling structure 4300, and a display engine 4400. A light beam 4201 guided by the display engine 4400 to the input coupling structure 4200 can be coupled into the waveguide 4100 through the input coupling structure 4200, and the light from the light beam 4201 can then be coupled out of the waveguide 4100 through the output coupling structure 4300, directed toward the user's eyes.

[0086] It should be understood that the above embodiments can be used in combination with each other. Two or more embodiments can be combined together to form further embodiments.

[0087] It will be apparent to those skilled in the art that the basic idea of ​​this invention can be implemented in various ways as technology advances. Therefore, this invention and its embodiments are not limited to the examples described above, but can be varied within the scope of the claims.

[0088] It should be understood that any of the above benefits and advantages may relate to one embodiment or multiple embodiments. The embodiments are not limited to embodiments that solve any or all of the described problems or that have any or all of the described benefits and advantages.

[0089] The term "comprising" is used in this specification to mean that a feature or action is included thereafter, but does not exclude the presence of one or more additional features or actions. It should be further understood that references to "a" an item refer to one or more of those items.

Claims

1. A display structure, comprising: The waveguide includes a first surface extending laterally along a reference plane, a second surface opposite to the first surface, and an input coupling region located on the first surface; An input coupling structure is used to couple a light beam into the waveguide via the input coupling region so that it can propagate in the waveguide by total internal reflection; The output coupling structure is configured to perform outgoing pupil expansion by pupil replication along at least a first replication direction and couple light from the beam to the outside of the waveguide; wherein the input coupling region has a maximum width Wmax measured along the first replication direction; the waveguide has a thickness T measured from the first surface to the second surface, which is greater than 0.25 times the maximum width Wmax of the input coupling region; and the output coupling structure includes a diffracting first output coupling element and a diffracting second output coupling element that at least partially laterally overlaps the first output coupling element, wherein the output coupling structure further includes a diffracting third output coupling element disposed within the waveguide, the third output coupling element at least partially laterally overlapping each of the first output coupling element and the second output coupling element, and wherein the third output coupling element includes a volumetric holographic diffraction grating.

2. The display structure as described in request item 1, wherein, The thickness T of the waveguide is greater than or equal to 0.3 times, 0.35 times, or 0.4 times the maximum width Wmax of the input coupling region.

3. The display structure as described in request item 1, wherein, The input coupling structure includes a diffraction input coupling element.

4. The display structure as described in request item 1, wherein, The input coupling structure includes an input coupling prism.

5. The display structure as described in request item 1, wherein, The first output coupling element is disposed on the first surface, and the second output coupling element is disposed on the second surface.

6. The display structure as described in request item 1, wherein, The thickness T of the waveguide is greater than or equal to 0.5 times, 0.6 times, 0.7 times, 0.8 times, or 0.9 times the maximum width Wmax of the input coupling region.

7. The display structure as described in request item 1, wherein, The thickness T of the waveguide is less than or equal to 0.5 times the maximum width Wmax of the input coupling region.

8. The display structure as described in request item 1, wherein, It also includes a display engine for guiding the beam to the input coupling structure.

9. The display structure as described in claim 8, wherein, The display engine is implemented as a scanner-based display engine.

10. A display device comprising a display structure as described in any one of claims 1 to 9.

11. The display device as claimed in claim 10, wherein, The display device is implemented as a transmissive display device.

12. The display device as described in claim 10 or 11, wherein, The display device is implemented as a head-mounted display device.

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